as far as I can tell, it does not matter where you put the 3s and 9s in this puzzle, as long as they are opposite eachother...thus allowing for TWO answers to this puzzle. A minor loophole yes, proving that "all sudokus only have one solution wrong" yes as well :p

IMO, most puzzle creators strive to ensure their published puzzles only have one solution, but that does not preclude anyone from publishing puzzles that have more. A puzzle that has more than one solution is not solvable by logic alone, which means it basically violates the spirit if not the definition of a Sudoku, rendering it a non-Sudoku. A valid Sudoku has one and only one solution and there are plenty of those around. Don't waste time on the others.